Bacterial sporulation represents an ideal system in which to study the differential control of gene expression during a simple cell differentiation process. The possibilities for control of bacterial development by alterations in RNA polymerase structure will be investigated in Bacillus subtilis. Single site RNA polymerase mutants and serine protease mutants which cause sporulation, but not vegetative growth, to become temperature sensitive will be studied by genetic and biochemical techniques. It is hoped the results of this project will further our understanding of the mechanisms which control normal and abnormal cell development. Bibliographic references: Freese, P.K. and Leighton, T.J. Bacillus subtilis RNA polymerase modification during sporulation. Paper presented at the Pacific Slope Biochemical Conference, June, 1975, Honolulu, Hawaii. Leighton, T.J. (1974) J. Mol. Biol., 86,855.